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United States Patent | 5,032,708 |
Comerford ,   et al. | July 16, 1991 |
A write-once-read-once batteryless token stores access data using fuses similar to those found in programmable fuse link devices. These fuses indicate the status of a particular bit in either of two memory arrays. An intact fuse indicates that a bit is a logical zero, and a blown fuse indicates that a bit is a logical one. The process of reading a particular bit in either array causes the destruction of the corresponding memory cells in both arrays before the data from the selected cell becomes available to the reading device. The memory bit cells are destroyed by blowing the bit fuse during the read cycle.
Inventors: | Comerford; Liam D. (Carmel, NY); Shrauger; Vernon E. (Somerville, MA) |
Assignee: | International Business Machines Corp. (Armonk, NY) |
Appl. No.: | 391912 |
Filed: | August 10, 1989 |
Current U.S. Class: | 235/492; 235/441; 235/487; 365/96 |
Intern'l Class: | G06K 019/06 |
Field of Search: | 235/487,492,380,381,382,441 365/96 |
3544769 | Dec., 1970 | Hedin | 235/492. |
4734885 | Mar., 1988 | Luich | 365/96. |
4773046 | Sep., 1988 | Akaogi et al. | 365/96. |